General David Petraeus resigned from his post on Friday, citing an extramarital affair. Now Slate has revealed that the person with whom he had the affair was his biographer, Paula Broadwell. Raised in North Dakota, the author, 39, lives with her husband in North Carolina with their two sons.

Sources tell me that President Obama, who has been getting along with Petraeus very well in the past couple years, agonized for 24 hours over the letter of resignation before accepting it. The move no doubt ends the career of the most famous, and perhaps most strategically astute, American military commander in decades ...

It had long been rumored that something was going on between Petraeus and Broadwell. Her book, co-written with Vernon Loeb, is widely regarded as a valentine to the general. When she was embedded with him in Afghanistan, they went on frequent 5-mile runs together. But Petraeus went on 5-mile runs with many reporters, and few people who knew him took the rumors seriously. In his personal life, he’s always been seen as a straight shooter, a square. Few could have imagined that his end would come as the result of a morals scandal.